The long-term goal of this project is to develop a passive monitor for measurement of cumulative exposure to organophosphate (OP) pesticides. This monitor is based on the innovative exploitation of the anchoring of liquid crystals to a surface functionalized with metal ions. In Phase 1, we demonstrated the ability to select combinations of metals that would selectively bind OPs and to design multi-arrays of metals to identify individual OPs. We also demonstrated the use of this new technology to measure cumulative exposure to ppb concentrations of commercial formulations of OP pesticides over a three-week period. The surfaces we created were not affected by humidity and exhibited stability. These data strongly support the feasibility of Platypus TM technology as the basis of small, inexpensive, rugged passive monitors suitable for measuring cumulative pesticide exposure in children and adults. In Phase 2, we will examine the effects of potential interfering compounds, we will calibrate our prototype monitors against standard sampling methods under laboratory and field conditions and we will optimize choice of materials, housing, and read out methods to incorporate in the design of a field prototype monitor. This prototype will be tested under field conditions to determine precision and accuracy. [unreadable] [unreadable]